Multi-objective Optimization And Control Strategy Of Hybrid Electric Vehicle Based On Genetic Algorithm

Hybrid electric vehicles in the energy consumption and emissions performance is better than the internal combustion engine car,in the driving range is better than pure electric vehicles,in reducing fuel consumption,improve vehicle transport efficiency has a prominent advantage.Power transmission system is the core of hybrid vehicles,transmission system parameters to determine the vehicle power and fuel economy have a great impact.Based on the multi-objective optimization theory and method,this paper designs the multi-objective optimization of the parameters of the hybrid vehicle drive system to complete the optimal matching selection of the engine and the powertrain system,and realizes the purpose of enhancing the power and fuel economy of the hybrid electric vehicle.The main work of this paper is as follows:(1)Based on the existing models,the mathematical model,the mathematical model of the motor,the mathematical model of the driveline and the mathematical model of the running resistance are established respectively.The mathematical model of the driveline includes: the mathematical model of the transmission,the interval ratio mathematical model of the gear ratio and the transmission ratio mathematical model.(2)Establishment of multi-objective optimization model for hybrid electric vehicle transmission system.With the dynamic and fuel economy as the double objective function,the dynamic objective function is the acceleration ability(in situ acceleration time),and the fuel economy objective function is the mixed fuel consumption of 100 km.The vehicle dynamic constraint,constraint ratio and prevent power interruption constraints as constraint conditions,the main reducer gear ratio and gear ratio of transmission as design variables,the multi-objective optimization design theory and method based on established multi-objective optimization mathematical model of the power transmission system of hybrid vehicle.(3)Multi-objective optimization of powertrain for hybrid electric vehicles.Based on the proposed multi-objective optimization mathematical model,based on the non-dominated multi-objective optimization algorithm(NSGA-II)with elite strategy,the specific parameters of the NSGA-II optimization process are set,the multi-objective optimization of the power transmission system parameters,obtain a series of uniformly distributed Pareto optimal solutions,and finally select a group of relatively low fuel consumption solution as the optimal solution for this paper.The working mode ofhybrid electric vehicle is analyzed,and the optimal control strategy of the power source torque is established with the optimal economic efficiency of the engine as the control target.(4)Multi-objective optimization method and verification of control strategy.Using the ADVISOR simulation platform to simulate the vehicle dynamics and fuel economy,this paper uses the power supply torque coordination and distribution control strategy of hybrid electric vehicle,and compares the vehicle performance before and after optimization to verify the multi-target transmission based on NSGA-II The practicality and effectiveness of system optimization design and control strategy.The simulation results show that the optimal design of the power transmission system parameters under the NEDC condition can effectively improve the vehicle dynamic performance and reduce the fuel consumption,and provide some theoretical support and method guidance for the optimal design of the hybrid powertrain.